Plate-shaped inductor for inductive high-frequency heating



1957 D. c. VAN IPEREN 2,809,264

PLATE-SHAPED INDUCTOR FOR INDUCTIVE HIGH-FREQUENCY HEATING Filed Aug. 3,1953 /o 712 I3 1 3 J? INVENTOR DIRK CHRISTIAAN VAN IPEREN United statesPater,

2,809,264 Patented Oct. 8, 1957 PLATE-SHAPED INDUCTOR FOR INDUCTIV EHIGH-FREQUENCY HEATING Dirk Cliristiaan van Iperen, Eindhoven,Netherlands, assignor, by mesne assignments, to North American PhilipsCompany, Inc., New York, N. Y., a corporation of Delaware ApplicationAugust 3, 1953, Serial No. 371,896

Claims priority, application Netherlands October 16, 1952 4 Claims. (Cl.21910.79)

The invention relates to a plate-shaped inductor for inductivehigh-frequency heating which is characterized in that at least one ofthe sides forming the boundaries of the working opening is provided withan aperture, of which the edge adjacent the working opening is at leastpartly substantially parallel to the edge of the working opening insitu.

This has the advantage that at the said area the electromagnetic fieldneed not pass through the electrically conductive material of theinductor, so that the losses are reduced and a desirable stron erheating is obtained at that area.

According to a further feature of the invention the plate-shapedinductor is provided with at least two apertures one on each side of theinsulation between the supply points of the inductor, preferably insymmetrical arrangement.

The disadvantage inherent in the use of the conventional plate-shapedinductors in that the heating of the work piece in the proximity of theinsulation is frequently insufiicient to meet the requirements is thusmitigated.

In order that the invention may be readily carried into effect, it willnow be described with reference to the accompanying drawing.

Referring to Fig. 1, the plate-shaped inductor 1, having a workingopening 2, is provided with an aperture 3 in one of the sides, the edge4 of the aperture on the side of the working opening 2 being parallel tothe edge 5 of the working opening in situ. Thus the inductiveelectromagnetic field is capable of completing itself unhindered throughthe aperture 3 about the uniformly wide strip 6 of the inductor 1, as isindicated by arrows, since the resistance of the material of theinductor is absent at this area. If desired, the aperture may be filledout more or less by a material having high permeability, for example, aferrite, so that the field may be further intensified.

The inductor shown in Fig. 1 is furthermore provided with two additionalapertures 8 and 9 symmetrically one on each side of the insulation 7,for example, an air gap, he edges iii and 11 of these apertures beingparallel to he inner wall 12 of the inductor. Thus also the heating ofthe work piece at this area is improved, so that the harmful effect ofthe air gap 7 may be more or less compensated. Moreover, the current isthus compelled to flow more along the corners 13, so that the length ofthe path is increased along the edge 1.2.

Referring to Fig. 2, the two apertures 14 and 15 open in the outer edges16 and 1'7 of the inductor, so that the full current is compelled toflow along the corners 13 and an increased effect is obtained. Anadditional aperture 18 is provided on the side opposite the work piecein order to enhance the heating.

Such inductors are of particular importance for highfrequency solderingof iron tins and the like.

What is claimed is:

1. A C-shaped, plate-like inductor for high frequency heating defining aworking aperture and having an air gap between the ends of saidinductor, an elongated opening completely throu h and completelysurrounded by the material of said inductor adjacent said workingaperture having at least one bounding edge thereof substantiallyparallel to the adjacent edge of said working aperture.

2. A C-shaped, plate-like inductor as set forth in claim 1 wherein amaterial having a high permeability is contained in said elongatedopening.

3. A C-shaped, plate-like inductor as set forth in claim 1 furtherincluding a pair of apertures in the ends of said inductor adjacent tosaid air gap.

4. A C-shaped, plate-like inductor as set forth in claim 1 furthercomprising at least one recess in the outer marginal edge of saidinductor and in a position adjacent said air gap.

References Cited in the file of this patent UNITED STATES PATENTS2,128,086 Gakle Aug. 23, 1938 2,314,865 Bierwirth Mar. 30, 19432,456,091 Stevens et al. Dec. 14, 1948 2,641,682 McKenna June 9, 19532,692,934 Williamson Oct. 26, 1954 2,714,648 Blok et al. Aug. 2, 1955FOREIGN PATENTS 740,385 Germany Sept. 2, 1943

